--> ABSTRACT: GLORIA Mosaic of the U.S. Hawaiian Exclusive Economic Zone, by Michael E. Torresan; #90097 (1990).

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ABSTRACT: GLORIA Mosaic of the U.S. Hawaiian Exclusive Economic Zone

Michael E. Torresan

Digital long-range side-scan sonar reconnaissance surveys using GLORIA have imaged about 65% of the nearly 2.4 million km2 of the Hawaiian EEZ. The images have been processed and compiled into one mosaic that comprises the EEZ area surrounding the principal Hawaiian islands (from Hawaii to Kauai); extending on the south side of the ridge west to Kure Island, and on the north side to St. Rogatien Bank.

The GLORIA images depict a variety of features that include enormous slumps and debris avalanches, lava flows, seafloor spreading fabric, fracture zones, seamounts, and unusual sedimentation patterns with more detail than previously had been possible with typical seismic reflection techniques. Some of these features were unknown before the GLORIA surveys. In particular, the GLORIA images show that the major degradational processes that affect the island and ridge areas are massive, likely tsunamogenic, blocky debris avalanches and slumps. These failures mantle the flanks of the ridge; some extending across the trough and up on to the Hawaiian Arch (up to 230 km from their sources). Over 30 failures are identified, ranging in area from 250 to >6000 km2, and having volumes from 500 to >5000 km3. Such deposits cover >125,000 km3 of the Ridge and adjacent seafloor.

Also imaged are large Cenozoic submarine volcanic flow fields situated on the Hawaiian Arch. One such field, the North Arch field, is located north of Oahu between the Molokai and Murray fracture zones, and covers about 200,000 km2. Prior to the GLORIA imagery only a small portion of this flow field was mapped. In addition, the imagery depicts the finer details of the Molokai and Murray fracture zones, the Cretaceous seafloor spreading fabric, and tensional faults on the Hawaiian Arch. This imagery has led, and will continue to lead, to a better understanding of the seafloor spreading history, the loading and flexural features of the crust, and sedimentary provinces associated with this portion of the Pacific Plate.

AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990